Such a fluid reservoir is known from prior art, for instance, WO 98/32539. This fluid reservoir is provided for one time use and comprises a container of plastic and a lid that can be placed thereon to close off the container. On the lid, connecting means are provided for placing the fluid reservoir on and fastening it to a paint spray gun or an adapter mounted thereon. In this case, the fluid reservoir is placed “upside down” on the paint spray gun, i.e., with lid side down. The paint present in the fluid reservoir then flows by gravity downwards into the paint inlet channel of the paint spray gun. In order to allow the gravity driven flow of paint, it is necessary for the pressure in the interior and that in the environment to be equalized. In order to guarantee this equalization, a ventilation part that can be closed by means of an adhesive tape or a manually operable valve is made in the container's bottom.
All the devices from prior art for closing the ventilation part have proved inadequate with regard to their tightness. Even with a valve mechanism, it cannot be reliably assured that paint will not escape through the ventilation part when the paint filled fluid reservoir is set down on its base.
Starting from this point, the invention is based on the problem of refining the fluid reservoir as known from prior art such that a flow of paint through the ventilation part is reliably prevented.